1. The Field of the Invention
The present invention is related to an apparatus and process for measuring the gap and mismatch of two adjacent surfaces. More particularly, the present invention is related to an apparatus and process for projecting two planes of light on adjacent surfaces and capturing and analyzing the resulting images to thereby calculate the gap and mismatch.
2. Technical Background
One step in the manufacture of automobiles and airplanes is the installation of body panels. Body panels are designed to simulate a continuous skin or covering about the vehicle. Body panels may be used to enhance the aerodynamic characteristics of the vehicle as well as provide the vehicle with an aesthetically pleasing shape.
The aesthetic and aerodynamic properties of a body are generally improved by ensuring that the distance between adjacent body panels is consistent and that the surfaces of adjacent panels follow the same contour. These qualities are generally quantified as the "gap" and "mismatch" of two adjacent surfaces. Thus, as used herein, the term "gap" refers to the end-to-end separation of two adjacent surfaces, as measured in the plane of one of the surfaces. The term "mismatch" means the surface-to-surface separation of two adjacent surfaces as measured in the direction perpendicular to the plane of one of the surfaces.
Thus, the quality of fit of two adjacent surfaces may be quantified and analyzed by measuring the gap and mismatch at several locations along the border of the surfaces. One of the most common methods for measuring gap is to employ an inside caliper or micrometer. Such an instrument includes jaws which are inserted into the gap and expanded until each comes into contact with the surface defining the gap. The size of the gap can then be read off marks on the instrument which measure the amount of extension of the jaws.
For applications requiring tight tolerances, this manual method for measuring gap is disadvantageous because of its limited accuracy. The operator of the instrument must ensure that the caliper is inserted in precise perpendicular orientation to the length of the gap. Additionally, because the jaws must contact the surfaces, there exists the possibility that the surfaces may deflect slightly upon contact, thereby providing a false reading.
Measuring mismatch is even more difficult and less precise. Typical prior art methods for measuring mismatch involve placing a straight edge along one surface such that it extends across the gap. An inside caliper or micrometer may then be employed to measure the distance between the second surface and the extended straight edge.
Of course, the accuracy of such a process depends greatly on the ability to accurately lay the straight edge along one of the surfaces. If, for example, the surfaces are curved, it may be impossible to accurately measure mismatch using this method.
In many circumstances it is desirable to keep a record of the gap and mismatch of body panels at various predetermined points. When utilizing the prior art methods described above, this data is generally manually recorded. Of course, when data is manually recorded there exists the possibility of human error resulting in inaccurate data being recorded.
In addition to the inherent limitations of accuracy, another significant disadvantage of using the manual processes described above to measure gap and mismatch is the amount of time required to take the measurements. To measure gap and mismatch at a single location, gap and mismatch must be independently measured and recorded before moving to measure the next location. As a result, thorough quantitative inspections of body panels are prohibitively expensive to perform in many applications.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide an improved apparatus and process for measuring gap and mismatch. Indeed, it would be an advancement in the art if such an apparatus and process provided increased accuracy over existing manual methods, thereby enabling tighter tolerances to be achieved in the fitting of body panels.
It would be an additional advancement in the art if such an apparatus and process for measuring gap and mismatch could automatically record data, thereby eliminating the possibility of human error in the recordation of data.
It would be a further advancement in the art if such an improved apparatus and process could be utilized to quickly measure gap and mismatch at a variety of locations, thereby rendering quantitative inspections of body panels economically viable and enabling superior fit of body panels to be achieved.
Such a method and apparatus is disclosed and claimed herein.